This invention relates to an improved frangible or breakaway valve in a flexible circular tube, principally for use in conjunction with a peritoneal dialysis solution container or blood bag.
Currently, the most widely used method of kidney dialysis for treatment of End Stage Renal Disease (ESRD) is "hemodialysis". Here, the patient's blood is cleansed by passing it through an artificial kidney in an artificial kidney dialysis machine. By the process of diffusion across a semipermeable membrane in the artificial kidney, impurities and toxins are removed from the patient's blood to thereby perform a function of the patient's natural kidneys. Hemodialysis is required several times a week, each dialysis requiring several hours in a dialysis center or at home. During dialysis, the patient is "tied" to the machine by venous and arterial blood lines which convey his blood to and from the artificial kidney.
Although used less frequently than hemodialysis, a procedure known as "intermittent peritoneal dialysis" is an accepted method for treating ESRD. In this procedure, a dialysis solution is infused into the patient's peritoneal cavity by means of tubing and a catheter. The peritoneum, which defines the peritoneal cavity, contains many small blood vessels and capillary beds which act as a natural semipermeable membrane. This natural membrane may be contrasted with the artificial membrane used in hemodialysis. In both cases, however, impurities and toxins in the blood are removed by diffusion across a membrane--a cellulose membrane of an artificial kidney or a peritoneal membrane of a peritoneal cavity.
In intermittent peritoneal dialysis, dialysis solution remains in the patient's peritoneal cavity for a time sufficient for blood impurities to be removed by diffusion across the peritoneal membrane into the dialysis solution. The impurity containing dialysis solution then is drained from the peritoneal cavity by means of the catheter and tubing, and a fresh supply of dialysis solution is infused. Intermittent peritoneal dialysis utilizes pumps or other auxiliary equipment to which the patient is "tied" during dialysis; here also the patient must remain sedentary.
Continuous ambulatory peritoneal dialysis is another type of peritoneal dialysis which uses the peritoneum as a semipermeable membrane. This procedure has the important advantage, however, of enabling the patient to be ambulatory and conduct a normal routine during dialysis. The patient is not "tied" to a machine and he must be sedentary only for the time period required to drain and infuse dialysis solution from and into the peritoneal cavity. This infusion and draining is handled by tubing and a surgically implanted, indwelling catheter in the patient's abdominal wall and in communication with his peritoneal cavity.
The continuous ambulatory peritoneal dialysis procedure is intended to be a patient self-care technique once the catheter is surgically implanted. Thus, it is important that the apparatus involved, e.g., tubing and solution container, be simple and easy to use. The present invention is intended to simplify the procedure for infusing dialysis solution into the peritoneal cavity. The invention concerns a novel breakaway valve in the tubing which is attached to or may be a part of the peritoneal dialysis solution container.
Breakaway valves in flexible tubes for use in blood bags are known in the art. The prior art valves typically consist of two parts: a hollow tubular portion bonded to the interior of a flexible tube and a rigid breakaway portion or handle integral with the hollow tubular portion. The handle is breakable by manual manipulation. After breaking, it moves away from its interface with the tubular portion and fluid can flow past it and through the tubing.
An example of a frangible valve in a blood bag is shown in Yoshino U.S. Pat. No. 4,007,738. Here the valve is opened by manually breaking a reduced annular section to effect fluid flow within the blood bag tubing, the breakaway portion floating freely within the tube. Another frangible valve used in a blood bag is shown in French Pat. No. 2,098,873. Here the breakaway portion falls into the blood bag. In U.S. Pat. No. 4,181,140 of Edward L. Bayham, et al.; U.S. patent application Ser. No. 15,395 of Carter, et al., filed Feb. 26, 1979; and U.S. patent application Ser. No. 64,952 of Elvis E. Adams filed Aug. 8, 1979, all owned by the assignee of this application, frangible valves for flexible tubes in conjunction with blood bags are disclosed. These two patent applications and the patent show frangible valves of various embodiments, some with locking hold-open means. In all prior art breakaway valves, fluid flow is in one direction only. The force of the fluid flow tends to push the broken away part of the valve away from the opening. In practicing the continuous ambulatory peritoneal dialysis procedure fluid flow will be in two directions--one direction during infusion, and the opposite direction during drain.
Some disadvantages of the known frangible valves include: (1) the inability to assure that the breakaway portion will remain in an open position after being broken, (2) the complex configuration required to lock the breakaway portion in a hold-open position, and (3) the difficulty in manually breaking the valve and moving it to an open position. The latter disadvantage is particularly significant when a person does not have good manual dexterity or strength.
Thus, there is a need to provide a frangible valve in a flexible tube which can be easily broken and moved to and remain in an open position. A valve configuration which is simple in design is also desirable for ease of molding and manufacture.
With the advent of dialysis solutions contained in plastic bags, and the development of continuous ambulatory peritoneal dialysis, a simple frangible valve for use by patients in establishing flow from a peritoneal dialysis solution bag via tubing and a catheter to the patient's peritoneal cavity is desired. A simple effective frangible valve which after breaking will remain locked in a hold-open position would, in addition to its potential use in blood bags, be important, particularly from a patient self-care standpoint, when practicing continuous ambulatory peritoneal dialysis. It is, therefore, an object of this invention to provide an improved frangible valve in a flexible tube which has a simple, effective hold-open feature for use in peritoneal dialysis solution bags for continuous ambulatory peritoneal dialysis patients, is easy to open, and easy to move to a hold-open position.
Breaking of the valve of this invention is done by bending the exterior of the flexible, circular tubing back upon itself at the point where the handle joins the closed end of the tubular portion. The initial bending action, and subsequent bending, will "walk" the handle down the tube and away from the now opened tubular portion. Ease of breaking is important for the practice of continuous ambulatory peritoneal dialysis because of the large number of patients with limited physical capacity because of poor eyesight, weakness, arthritis and the like. This invention also is particularly advantageous for use by children and geriatric patients for these same reasons.
The valve of this invention remains in a hold-open position because of projections on the handle. They frictionally contact the interior of the flexible tube; they tightly grip or "bite" into the soft, flexible tubing. Some of the known breakaway valves used in blood bags have provided for frictional contact at a special reduced conical section in the tube. The valve of this invention eliminates the need for any special insert or section (conical, or otherwise) in the tube to hold the broken away handle. The size of the flexible, circular tubing can remain constant, unlike existing blood bag valves with hold-open means in which the valve is locked into a conical section of tubing of reduced cross section.